SIBO/EPOC OPO (Compiled OPL source code) interpreter written in Python. Supports the SIBO (Psion 3 Series) intermediate QCode Opcode set.
This project has taken OPO as a grey box - it is not pure black box implementation due to prior works, however other interpreters and runtimes have not been simply ported to Python, this interpreter has been built from the ground up.
Some features may be anarchic or seem inefficent, this was due to the interative nature of development (a hobby project); this project was made as an adventure in understanding into CPythons internals and the wider concept of interpreters/compilers and runtime environments. Thus development was iterative as more complex compiled OPL programs were run.
OPL and associated QCode is interesting in that it is a very high level language, encorporating OpCodes and functionality that would usually be built into libraries rather than language itself. These include a Database Management System (DBMS) and feature rich Graphics, expanding the OpCode set to just under 300!
- Filesystem abstraction and support for various EPOC/SIBO file types (DBF, SPR)
- Multi-module support via LOADM
- A range of common system calls (CALL & OS) are emulated
- Most graphical operations and modes are supported (limited inverted drawing is supported at a slower render speed)
- Emulation of standard SIBO menus and Dialogs
Example code and applications downloaded from the internet, running in the PyOpo interpreter. Some feature the attached Debugger tooling:
Understanding of some functionality in the OPL runtime has been gleamed by the following sources:
- PSIONICs and RevTran derived qcode.txt
- OpoLua
- opl-dev
Without an operational PSION or emulated environment, verification of opcode edge cases via test is not possible.
This interpreter can only execute pure OPL derived OpCodes, extended interop into ARM via USR calls is not currently emulated, nor likely will be.
The interpreter is currently configured to support SIBO instructions and behaviour, EPOC behaviour is possible however it requires manual alterations.
Over and underflow errors are not currently checked at runtime by the interpreter.
The interpreter utilises a dynamic heap containing data frames, however the debugger stores a lookup dictionary of offset locations and variable metadata. This was done as they are solving different problems. The debugger does not verify or store information about memory allocation operations.
Currently global locations are not reserved in the heap, and are only 'pinned' to the first active procedure that declared it. If that procedure has returned, the reference to the global is lost. It is unknown (untested) whether this is expected behaviour
This runtime does not include any example applications. To use it:
- Download an OPA (search for 'Psion OPA' or 'Psion 3 games' online)
- Unpack the app into DRIVE\M\APP\ or according to the apps instructions
- Update 'executable_location' in launcher.py
- Run launcher.py
- (Missing) Ability to load specific formats - .WVE
- (Missing) Audio functionality - System calls are stubs
- (Incomplete) Invert drawing mode
- (Incomplete) Database functionality
- (Missing) USR calls
- (Incomplete) CALL and OS functionality
- (Incomplete) DIALOG functionality (dTIME, dFILE)
- (Missing) Most extended 0xFF OpCodes
- (Missing) EPOC Colour support
- (Missing) Toolbar support
PyOpo is licensed under the MIT License (see LICENSE).